Osama bin Laden’s son-in-law Sulaiman Abu Ghaith told authorities he heard “something big was going to happen” before 9/11 but claimed he was never informed about the depths of al Qaeda’s terror plot, an FBI agent told Manhattan jurors Thursday.

Testifying at Abu Ghaith’s terror trial in federal court, Agent Michael Butsch said the former al Qaeda spokesman told him he had been summoned to bin Laden’s home after the Sept. 11, 2001, attacks.

“Bin Laden first asked him, ‘Did you see what happened?’ He said he did, and bin Laden said that he did this operation,” recalled the agent, who questioned Abu Ghaith aboard a 14-hour flight from Jordan to New York last year.

At bin Laden’s request, Abu Ghaith would then make a series of videotaped speeches, including one on Sept. 12, 2001, with bin Laden and other al Qaeda honchos beside him.

“He said the purpose of these videotapes was for propaganda, to get them out into the media,” Butsch recalled.

In one video, on Oct. 9, 2001, Abu Ghaith threatened that “America must know that the storm of airplanes will not abate.”

Abu Ghaith, 48, faces life in prison if convicted of conspiring to kill Americans and of providing material support to al Qaeda.